Specialists currently consider that a common cause of skin impairments, accelerated cellular aging and several dermatosis is the reduced defense and/or the overesponse to free radicals and subsequent oxidation phenomena.
Unfortunately the prevalence of dermatological disorders is increasing due to several environmental factors, possibly related to the oxidative stress, as described by Hallywell B in “Reactive oxygen species (ROS) in pathology with special reference to the skin” (Oxidative Stress in Dermatology—eds. Marcel Dekker Inc, New York, 3-11, 1993). Oxidative stress on skin may be prevented in different ways, as pointed out by Sies H in “Strategies of antioxidant defense” (Eur J. Biochem. 215: 213-219, 1993).
Exemplary, the atopic dermatitis (AT) is often the result of inherited sensitivities to an unknown allergen, most likely ROS, thereby manifested as redness, itching and oozing lesions that eventually scab over. This common inflammatory condition is spread out in young children and infants, more rarely appearing into adolescence and adulthood whilst, in some cases, the first symptoms show up later in life.
Singlet Oxygen (1O2) is an uncharged, low reactive ROS, whose characteristics allows its penetration and diffusion in the deep dermal layer and into cytoplasmatic fluids, where it may produce allergy and inflammation.
Beside accelerating skin-ageing, 1O2 may produce dermatological disorders such as atopic dermatitis, psoriasis, allergic and inflammatory dermatitis, acne, rosacea and porphyria, erythemas, and so on.
The formation of 1O2 is prompted by UV radiation and further promoted by p-amino benzoic acid (PABA) and others common UV-absorbers.
An efficient 1O2 trap is furfuryl alcohol, a natural by-product quickly reacting with 1O2 at room temperature by Diels-Alder cycloaddition, for example in tests carried out in an irradiated aqueous solutions PABA or photosensitizers and saturated with 02 (Allen J et al., in Chem. Res. Toxicol., 9, 3:605-609, 1996 and J Photochem Photobiol B, 32:1-2:33-7, 1996; Kimel S et al., J Photochem Photobiol, 50. 2:175-83, 1989).
While furfuryl alcohol is an unstable chemical used in polymer manufacturing and in organic synthesis, some stable furfuryl alcohol derivatives occur as vegetal metabolites.
Simple furfuryl esters, such as furfuryl acetate, amylate and caprylate occur in trace amount in essential oil, being applied by the aroma industry for the manufacturing of flavor and fragrance compositions.
A furfuryl glicoside, namely furfuryl-I-beta-glucose, is the activator of (1-3)-beta-glucan synthase in higher plants, as found out by Callaghan, T. in Plant Physiol. 86, 1099-1103 (1988) and Ohana P. in J. Biol. Chem., 266(21):13742-5 (1991).
A furfuryl nucleotide, namely kinetine (alias N6-furfuryladenine, furfuryladenine, or 6-furfuryl aminopurine), is a vegetal citokine with growth regulation role in plant cells, which has been applied as anti-iperproliferative and skin anti-ageing, as disclosed in U.S. Pat. No. 5,164,394 (Senetek, USA).
U.S. Pat. No. 5,13,594 discloses the topical use of 2,4-monofurfurylidene-sorbitol (furalglycitol), a synthetic furfural dichetal applied in cosmetic composition (Liktena™, UCB Corp.) with some results in the treatment of skin irritations.
However, furaglycitol tends to hydrolyze into sorbitol and furfural (furfurylaldehyde), which is at least twice as toxic as the furfuryl alcohol (Nomeir A A, Silveira D M, McComish M F, Chadwick M., Drug Metab Dispos 20(2):198-204, 1992). Hence, furalgycitol may not be recommended for chronic, repeated topical treatments.
Therefore, topical compositions comprising furfuryl derivatives capable of ameliorate the pro-inflammatory skin conditions on subjects over-responding to neutral ROS, which are furthermore easily applicable onto skin and displaying good tolerability and low toxicity, are still desired.